"Today, thanks to the incredible efforts of (Ukrainian energy) specialists, our nuclear power engineers and electricians managed to return the power supply to the Chernobyl nuclear power plant, which was seized by the Russian occupiers," Ukraine's Energy Minister German Galushchenko said in a statement.

"Our Ukrainian energy engineers, by risking their own health and lives, were able to avert the risk of a possible nuclear catastrophe that threatened the whole of Europe," he added.

Power had been cut to the site of the world's worst nuclear disaster, though the UN's atomic watchdog said there was "no critical impact to safety".

An explosion at the Chernobyl nuclear power plant in 1986 killed hundreds and spread a radioactive cloud west across Europe.

Ukraine said on Wednesday power had been cut to the plant, but the UN's atomic watchdog said there was "no critical impact on safety".

Russian forces also shelled and captured the Zaporizhzhia plant, Europea's biggest atomic power plant, on March 4, causing a fire that raised alarm in Europe over a possible nuclear catastrophe.

Russian engineers arrived at Zaporizhzhia earlier this week to check radiation levels.